This invention relates to a process for dewatering certain mineral slurries. More specifically, this invention relates to a process for dewatering aqueous slurries of aluminum ore, copper ore, iron ore, lead ore, molybdenum ore, and zinc ore by the use of a silicone glycol as a dewatering aid.
Valuable components of numerous minerals are concentrated by various procedures to provide mineral concentrates that are further processed. One of the most widely used methods of concentration is froth flotation which is applicable to a wide variety of minerals. After a mineral has been sufficiently enriched in valuable component by concentrating, it is usually subjected to dewatering so that it may be shipped more economically and/or further processed more readily. In dewatering, the mineral concentrate in slurry form is subjected to filtration or equivalent processing to remove water therefrom. The removal of water decreases the weight of the concentrate and also reduces the energy requirements for subsequent evaporation of residual water when necessary such as for smelting.
Both surfactants and flocculating agents have been employed to assist the dewatering of mineral slurries. For example, U.S. Pat. No. 4,207,186 (issued June 10, 1980) discloses that a mixture of a hydrophobic alcohol and a nonionic surfactant can be employed as a dewatering aid for mineral slurries. U.S. Pat. No. 4,210,531 (issued July 1, 1980) teaches the use of a combination of a flocculant, an anionic surface active agent, and a water insoluble organic liquid for mineral slurry dewatering. U.S. Pat. No. 4,231,868 (issued Nov. 4, 1980) teaches the use of N-substituted sulfosuccinanate as dewatering aids with mineral slurries. None of the above cited patents teach the use of any organopolysiloxanes as mineral slurry dewatering aids.
U.S. Pat. No. 4,290,896 (issued Sept. 22, 1981) discloses that a wide variety of organopolysiloxanes can be employed as dewatering aids for fine coal. The use of organopolysiloxanes as dewatering aids in the processing of mineral slurries was not taught nor disclosed in this patent. Indeed, U.S. Pat. No. 4,290,896 does not even allude to such a use. The organopolysiloxanes of U.S. Pat. No. 4,290,896 were described by the general formula EQU R.sub.a H.sub.b SiO.sub.(4-a-b)/2
where (a+b) varies from greater than zero to less than 4, b varies from 0 to a, and R is an organic radical bonded to a silicon atom by a silicon-carbon bond. R in the above formula denotes any organic radical, such as any hydrocarbon radical such as any alkyl, alkenyl, alkynyl, cycloaliphatic, aryl or arylalkyl radical, or any substituted hydrocarbon radical wherein said substituents include halogen, hydroxy, alkoxy, aryloxy, carboxy, carbalkoxy, amino, substituted amino, polyalkyleneoxy, mercapto, substituted mercapto, polyalkyleneimine, amide, nitro, and the like.
As is well known in the art, coal and mineral slurries are very different indeed. Coal slurries consist essentially of organic molecules whereas the mineral slurries consist essentially of inorganic molecules. Therefore, it is surprising that I have found that certain of the same organopolysiloxanes useful in the dewatering of fine coal are effective in the dewatering of minerals.
In spite of the effectiveness of dewatering aids which have been employed with mineral slurries, there nevertheless still exists the need for improved dewatering aids which provide lower residual water in the separated concentrate and/or more efficient separation of the mineral concentrate and which results in advantages thereby. Considering annual processing of many millions of tons of mineral ores, such advantages could provide substantial saving in shipping, processing, and capital costs. The provision for improved dewatering aids, therefore, would fulfill a long-felt need and constitute a significant advance in the art.
Therefore an object of this invention is to provide an improved dewatering aid for mineral slurries. Another object of this invention is to provide an improved dewatering aid for mineral slurries containing aluminum, copper, iron, lead molybdenum, or zinc ores.